Manufacture of metallic mirrors.



S. 0. COWPBR-OOLES. MANUFAGTURE OF METALLIC MIRRORS.

' I APPLICATION FILED NOV. 8, 1907. 9 1 5 ,4 1 5 Patented Mar. 16, 1909.

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S. 0. GOWP BR-OOLES FAGTURE 0F METALLIC MIRRORS.

APPL IIIIIIIIII ED NOV. 88888 7. 91 5 ,41 5 Patented Mar. 16, 1909.

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SHERARD OSBOBN COWPER-COLES, OF WESTMINSTER, LONDON, ENGLAND.

MANUFACTURE OF METALLIC MIRRORS.-

Specification of Letters Patent.

Patent'edfiaxch 1c, 1909. I

Application filed November 8 1907. Serial no. 401,318.

To allwh om it mag concern:

Be it known that I, 'SHERARD- OSBORN Cowman-Cows, a subject of the King of Great Britain, residing at Grosvenor Mansions, 82 Victoria street, Westminster, London, England, have invented new and useful Improvements in the Manufacture of Metallic Mirrors; andl do hereby declare that the following is a full, clear, and exact description of the invention, which will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to improvements in the manufacture of metallic mirrors which are especially suitable for use in connection with search-lights and head-lights.

It has not hitherto been ossible to successfully manufacture meta c mirrors since it is difficult to obtain cast or spun metal free from flaws and having a surface which, when highly polished, does not show the grain of the metal. Moreover, for spinniiig, comparatively thin metal has to be used which is not sufficiently rigid for a mirror of large di mensions.

The process described in the specification of my former British patent No. 5600 of 1895 was an improvement upon existing processes and the object of my resent inventionis to still further improve t e manufacture of mirrors of this kind. 7

According to myinvention I cast the mirror of any suitable metal such as iron, brass, gun-metal or German silver or I spin or stem sheet metal to the desired curvature. The 'ody is then placed in an electrolytic cell wherein a metal such as copper is deposited on the back thereof, unti it has obtained the desired thickness to make it rigid. I then lace the mirror in another electrolytic ce where silver, nickel or cobalt or a suitable silver allo is deposited upon its reflecting surface. he surface of'the mirror is then ground and polished. The above op- I 'erations may be repeated any number of times until a surface'is obtained which corresponds to that of glass. I may finally deposit upon the surface so prepared annular, radial concentric or like ands of gold or other suitable yellow metal, the object being to obtain white'and yellow beams which can be'well seen both by day and night and also in foggy weather. 1

To enable the invention to be fully understood I will describe it-by reference'to the accompanying drawing in which Figure 1 is a front View of a metallic reflector made according to the invention. Fig. 2 is a vertical section of the same, and Fig. 3 is a section of a portion of the mirror drawn to a larger scale. Figs. 4 and 5 are front views of two modified forms of mirror.

Referring first to Figs. 1, 2 and 3, a represtamped to the required curvature, is the backing such as copper; which is deposited upon the back of the metal form, a, and 0 represents the surface of the'reflecting metal which is deposited upon the surface of the form g.-.

Fig. 4 illustrates the formof a mirror in which the reflecting surface has deposited upon it annular rings (1,.(1 of gold or other suitable yellow metal, while in Fig. 5 the deposits of the yellow metal are in the form of radial bands e, e.

Having now particularly described and ascertained the natureof my said invention and in What manner the same is to be. performed, I, declare that what I claim is 1. The method of manufacturing metallic mirrors comprising, producing a metal form as copper and in then de ositing upon the surface a reflecting meta, after which the reflecting surface is ground or polished, substantially as described.

2. The method of manufacturing metallic mirrors comprising, de ositing a suitable metal upon the back 0 a formed metallic body and a reflecting metal upon the front surface thereof, after which the latter is grou'ndand polished and has deposited upon it, bands of a yellow reflecting metal, substantially as described.

' SHERARD OSBORN COWPER-COLES.

Witnesses:

Jenn El BoUsFrE n, C. G. REDFEBN.

sents the sheet of metal which is s un orof the desired curvature, electrolytically depositing upon the back thereof a metal such 

